What is the ruling on working and earning a salary in a software company that deals with currency exchange and stock market companies?

The ruling on creating software for exchange and stock market companies depends on the nature of their activities. If their activities are Islamically permissible, then there is no objection to it, and the mere possibility of their use in forbidden acts is not a concern. However, if their activities are predominantly Islamically impermissible, then it is not permissible to cooperate with them, as Allah Almighty says: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression" (Quran 5:2). If the worker's job does not involve forbidden programs, then there is no sin upon him. Otherwise, he must leave this work. As for the salary, it is lawful and does not take the ruling of mixed wealth, based on the opinion of most scholars who affirm the validity of selling what aids in sins, despite the sin incurred.